The present invention relates to fluid-tight seals and, in particular, seals for rotating shafts, which prevent passage of fluids axially along the shaft while accommodating rotation of the shaft. The invention has particular application to the type of rotating shaft seal in which an annular seal member is resiliently urged radially inwardly against the outer surface of the shaft.
It is known to provide a split-ring type of seal formed of carbon, graphite or the like, which is resiliently urged against the shaft by a garter spring. But such prior seal members are relatively brittle and unyieldable. In the event of any eccentricities in the shaft, such seal members are subject to uneven wear, which results in leakage.
It is also known to provide a somewhat flexible or resilient annular seal which has an outer edge thereof bonded to a bracket, the seal member being cantilevered from the bracket and having an inner end which is urged by a garter spring into sealing engagement with the shaft. While this construction affords some flexibility to accommodate eccentricities or irregularities in the shaft, such irregularities still encourage wear and, eventually, leakage will result because the outer end of the seal member is fixed. Furthermore, irregularities in the shaft cause uneven loading on the bonded end of the seal member, which tend to weaken the bond and can result in leakage at the secondary seal formed by the bond.